added

1 files changed, 16 insertions, 0 deletions

diff --git a/tree.py b/tree.py
new file mode 100644
index 000000000..84dd53084
--- /dev/null
+++ b/tree.py
@@ -0,0 +1,16 @@
+def build_tree (x):
+    if (x == ()): return ()
+    if (len (x) == 1): return (x[0],)
+    else: return (x[0], build_tree (x[1:]))
+
+def merge (a, b):
+    if a == (): return build_tree (b)
+    if b == (): return a
+    if b[0] == a[0]:
+        if len (a) > 1 and isinstance (a[1], type (())):
+            return (a[0],) + (merge (a[1], b[1:]),) + a[2:]
+        elif b[1:] == (): return a
+        else: return (a[0],) + (build_tree (b[1:]),) + a[1:]
+    else:
+        return (a[0],) + merge (a[1:], b)
+